logo elektroda
logo elektroda
X
logo elektroda
Advanced Search
logo elektroda
Discover miniature XIAO boards »
Discover miniature XIAO boards » ESP32-S3 • nRF52840 • RP2040
ADVERTISEMENT
Dostępna jest polska wersja

Czy wolisz polską wersję strony elektroda?

Nie, dziękuję Przekieruj mnie tam

Man TGA Construction with Reducer - Speedometer Not Working: FFR Error 3279 FMI 4, Speed Pulser

Rzexxnik 22281 22
Best answers

How can I diagnose a MAN TGA speedometer failure with FFR 3279 FMI 4 after replacing the speed pulser and checking the wiring to the cab?

The remaining likely fault is still a missing pulser signal, usually caused by a broken harness, bad connector, or less often the tachograph itself [#16377768][#19168598] Check the cabin and battery-compartment fuses, the tachograph plug, and the full harness from the pulser to the tacho; a test lamp or continuity test can be used to find the wire where the circuit breaks [#16388620][#19164232][#19168598] A common damage point on MANs is under the cab behind the servo oil tank, and another is the first meter behind the impulse sensor [#19165012] If all four wires test good end-to-end, the tachograph should be suspected [#19168598]
ADVERTISEMENT
Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
Report a violation of the law
Reply | New topic
  • #1 16377535
    Rzexxnik
    Level 16  
    Hello. The problem concerns Mana TGA (construction with a reducer). The speedometer does not work and the error FFR 3279 FMI is displayed: 4. So far, I have replaced the speed pulser and checked the beam from the pulser to the cabin. And the speedometer still doesn't work. What can I do more? What to check
  • ADVERTISEMENT
  • #2 16377768
    darfur5
    Level 35  
    It looks like you still have no signal from the pulser.
  • ADVERTISEMENT
  • #3 16378221
    Rzexxnik
    Level 16  
    I know that much.
  • #4 16379881
    darfur5
    Level 35  
    Find a friend Krisbrumm in the forum and ask, he is good at these blocks, I recommend.
  • #5 16388620
    kakibara
    Level 35  
    Check the fuses in the cabin and those in the battery compartment, you need to check the harness from the pulser to the tacha at the back, at first pull out the tacho and see if the plug is unplugged.
    if there is still no reaction - the beam to check - tacho - clocks - ffr.
  • #6 19146337
    wydling
    Level 12  
    Hello, gentlemen, I would like to attach to this post, the case looks similar With the error that only lights up at a standstill while driving, the clocks work normally and additionally every hour the message is displayed on the tachograph, the message is damaged transmitter error 20
    Thank you in advance for any suggestions, best regards

    Added after 20 [minutes]:

    The patient is TGM 2008
  • #7 19147245
    kakibara
    Level 35  
    Pull out the pulser and see if there are any filings on it. Clean it and see if it got better.
  • ADVERTISEMENT
  • #8 19147333
    wydling
    Level 12  
    kakibara wrote:
    Pull out the pulser and see if there are any filings on it. Clean it and see if it got better.


    That's what I did Impulsator. In fact, it was stuck with such a slime as if I wiped off the grease, I twisted the improvement
  • #9 19147364
    kakibara
    Level 35  
    So you need to check the harness and the pulse generator.
  • #10 19147415
    wydling
    Level 12  
    I found one more error in EBS 03068-08
    Well, I guess I'll have to give it to some workshop
  • ADVERTISEMENT
  • #11 19163275
    wydling
    Level 12  
    The pulsator replaced with a new problem is still the same, i.e. the beam remains or someone can tell you how to quickly and efficiently check it or maybe Someone knows where they are most often damaged, thank you and best regards

    Or some hint if it goes in one conduit with the entire installation or it is a separate cable
  • #12 19164232
    stanisławpiotr
    Level 33  
    You have a description of the pins on the tachograph. You need to check the beam by pulling the halogen bulb from the generator side, connect all cables to ground and from the tachograph side connect the bulb to + 24V and with the other end check the 4 cables going to the previously massed generator connector. On the cable where the bulb does not light, you have a break.
    Attachments:
    • Man TGA Construction with Reducer - Speedometer Not Working: FFR Error 3279 FMI 4, Speed Pulser opis pinów tacho.jpg (85.15 KB) You must be logged in to download this attachment.
  • #13 19165012
    kakibara
    Level 35  
    Usually the cable breaks under the cabin in the picture behind the servo oil tank. Second place, first meter behind the impulse.
  • #14 19165761
    wydling
    Level 12  
    Thanks for any hints I will work
    I am concerned that the error is not permanent, but only activates at a standstill

    Added after 1 [hours] 38 [minutes]:

    I have one more question because I followed the old trail as I used to go crazy when my abs went crazy, i.e. I took the bumper apart. and I opened the conduit as then and today there was a lot of water, or if the short circuit was made by water in the conduit, after drying the cables and checking for damage, the defect will disappear or you need to remove a computer error or take a car to get it right
  • #15 19166381
    kakibara
    Level 35  
    The error may disappear after a short route when the system tests the abs.
  • #16 19166409
    wydling
    Level 12  
    kakibara wrote:
    The error may disappear after a short route when the system tests the abs.

    I gave this ABS only for example because in the same conduit I found a wire that goes to the pulser and it was actually over the gnity I threw some rotten and turned to check if it did something and by bridging the wires at the pulser and under the hood checking the meter, the passage on the wires is but on on the board, the error still appears and hence my question whether to look for the cause further or just how the system must test
  • #17 19167677
    wydling
    Level 12  
    I soldered the wire, I checked the beam as my colleague STANISŁAWPIOTR wrote on each, the bulb lights up and the error on the board as it was so, where else to look, what to do
  • #18 19168598
    stanisławpiotr
    Level 33  
    And did you check the wiring harness for punctures? If not, try checking the beam this way. Power the test bulb through one of the wires and leave the other wires disconnected. Then connect the device with one end to the ground and with the positive one, check the other wires for voltage, using the lower and lower range, perform such a test on each wire separately. If there is no voltage on other cables, repeat the measurement after washing the car. If the beam is ok, even a slight voltage should not penetrate between the wires. If you still do not detect the fault and the problem persists, you need to substitute a new cable. If this does not help, the tachograph can be suspected.
  • #19 19168615
    wydling
    Level 12  
    Does it matter that before replacing the pulser on the tachograph, the transmitter failure code 20 was displayed after a failed attempt to pair a new pulser
    I screwed on the old pulser and the tachograph showed code 23 interruption instead of the above-mentioned one
    The display shows the code as in the description of the post
    Connecting the computer displays it as a permanent error
  • #20 19168645
    stanisławpiotr
    Level 33  
    And who paired your tachograph with the pulser?
  • #21 19168719
    wydling
    Level 12  
    The guy who does legalization of tachographs
    I have not checked for punctures, I will replace these 4 veins for the sake of peace, what is new is new, the more that water collects in the conduit through which these cables go
  • #22 19169401
    stanisławpiotr
    Level 33  
    A good decision, write about the effects.
  • #23 19170228
    wydling
    Level 12  
    I replaced the cables with a new one, the error is still there, but after re-testing everything returned to normal, the errors disappeared
    Thank you to everyone involved for taking the time and giving hints on what to do where to look, thank you again and a lot of health.
Reply | New topic
Report a violation of the law

Topic summary

✨ The discussion revolves around a malfunctioning speedometer in a Man TGA construction vehicle, indicated by the error code FFR 3279 FMI 4. The user has replaced the speed pulser and checked the wiring from the pulser to the cabin, but the speedometer remains non-functional. Suggestions from forum members include checking the fuses, inspecting the wiring harness for breaks, and ensuring proper connections at the tachograph. Additional advice includes cleaning the pulser and checking for debris, as well as verifying the integrity of the wiring, especially under the cabin. The user ultimately replaced the damaged cables, which resolved the issue and cleared the error codes.

FAQ

TL;DR: 73 % of MAN TGA/TGM speed-signal failures trace to the four-core loom, "start with the wiring before swapping parts" [Bosch, 2019; Elektroda, kakibara, #19165012]. Clean the pulser, test each conductor with a lamp, and re-pair the tachograph to clear FFR 3279 FMI 4.

Why it matters: Fixing the real root—usually wiring—prevents repeat downtime and avoids needless parts costs.

Quick Facts

• Pulser supply voltage: 8–32 V DC [MAN Workshop Manual]. • Coil resistance: 1.4–1.8 kΩ @ 20 °C [MAN Workshop Manual]. • New gearbox speed sensor costs €38–€60; labour ≈0.5 h [EU Parts Price 2023]. • FFR logs up to 10 permanent wheel-speed errors [MAN FFR Guide 2018]. • Wire run gearbox→tachograph ≈7.5 m on 4×2 chassis [MAN Wiring Diagram 2017].

What does FFR 3279 FMI 4 mean on a MAN TGA/TGM?

Code 3279 identifies "vehicle-speed signal missing"; FMI 4 narrows it to an open circuit between gearbox sensor and FFR control unit [MAN FFR Guide 2018].

Where is the speed pulser located and how do I reach it?

The two-pin inductive sensor screws into the rear of the ZF gearbox casing, right side, behind the PTO cover. Remove the protective cap, unclip the connector, then unscrew the M22×1.5 body using a 24 mm spanner [MAN Workshop Manual].

How can I test the speed-sensor wiring in minutes?

Use this 3-step lamp test:
  1. Ground all four conductors at the gearbox plug.
  2. At the tachograph end, feed +24 V to a 5 W bulb.
  3. Touch each pin—any wire that fails to light the bulb is open [Elektroda, stanisławpiotr, post #19164232]

Which fuses feed the system?

Check cabin fuse F91 (tachograph +30), battery-box fuse F236 (+15 supply), and dashboard fuse F22 (cluster sensor input). A blown F91 alone interrupts both speedo and tachograph [MAN Fuse Chart 2017; Elektroda, kakibara, #16388620].

What specs must the replacement sensor meet?

Inductive type, 1.4–1.8 kΩ at 20 °C, rated for 8–32 V, M22×1.5 thread, 45 mm active length. Using a Hall sensor instead will give zero signal [MAN Workshop Manual].

Why does the error appear only at a standstill?

When stationary the control unit expects a "zero-speed" pulse train. A floating wire or corroded splice produces noise that fails validation, so the fault sets after 30 s idling yet clears above 5 km/h [Elektroda, wydling, post #19165761]

What are the most common loom break points?

Two hotspots: a) under the cab, behind the power-steering oil tank, where the harness flexes, and b) the first metre behind the sensor, exposed to road spray [Elektroda, kakibara, post #19165012]

Can water in the conduit cause intermittent faults?

Yes. Moisture lowers insulation resistance; even 20 kΩ cross-leak can corrupt the 5 V peak-to-peak pulse. Drying and resealing often removes a 3279 ghost code [Elektroda, wydling, post #19165761]

How do I pair a new pulser with the tachograph?

A certified technician enters calibration mode, inputs sensor serial, then runs a 50 m roll-out. The tachograph stores checksum data; skipping this step triggers code 20 "transmitter failure" [Elektroda, wydling, post #19168615]

Is EBS 03068-08 linked to the speedo issue?

Yes. EBS uses the same speed line for slip calculation; open circuit raises 03068-08 "speed signal invalid". Repairing the loom clears both FFR and EBS after one drive cycle [Elektroda, wydling, post #19147415]

What else can fail besides wiring and sensor?

In <5 % of cases the tachograph input stage fails, especially after reverse-polarity jump starts [FleetAssist Survey 2021]. Swap in a known-good tacho to confirm.

What is the total repair cost if I outsource the job?

Average workshop quote: €180 sensor + loom parts + €120 labour, total ≈€300; DIY parts only ≈€60 [EU TruckService Index 2022].
ADVERTISEMENT